Drill jig for rotor of rotary mechanism

ABSTRACT

A drill jig for use in holding a rotor of a rotary mechanism in position adjacent a cutter drill when it is intended to bore or widen again a corner seal bore which has been eccentrically worn after use. The body of the jig is secured to the inner peripheral wall of the rotor for chucking the same in a proper position with respect to the rotor axis, and the center line of an apex seal groove is located and employed to correctly index the center line of the corner seal bore to be widened. Thus, the guidance of the cutter drill is carried out with its center line being located to fall substantially in a common plane shared between the rotor axis and the located center line of the apex seal groove and being spaced at a proper distance from and in parallel with the rotor axis. By use of this jig the worn corner seal member can be reshaped into a new member of slightly increased cross section making it possible to reuse the rotor as a whole without disposal of the expensive rotor proper.

United States atent [191 Nakada et ai.

[451 Aug. 20, 1974 DRILL .HG FOR ROTOR 0F ROTARY MECHANISM [75] Inventors: lllideo Nakada; Masao Ishikawa,

both of Hiroshima, Japan [73] Assignee: Toyo Kogyo Co., Ltd, Hiroshima-ken, Japan 22 Filed: May 17, 1972 21 App1.No.:254,096

[30] Foreign Application Priority Data Primary ExaminerAndrew R. Juhasz Assistant Examiner-Leon Gilden Attorney, Agent, or Firm-Stevens, Davis, Miller & Mosher ABSIRACT A drill jig for use in holding a rotor of a rotary mechanism in position adjacent a cutter drill when it is intended to bore or widen again a corner seal bore which has been eccentrically worn after use. The body of the jig is secured to the inner peripheral wall of the rotor for chucking the same in a proper position with respect to the rotor axis, and the center line of an apex seal groove is located and employed to correctly index the center line of the comer seal bore to be widened. Thus, the guidance of the cutter drill is carried out with its center line being located to fall substantially in a common plane shared between the rotor axis and the located center line of the apex seal groove and being spaced at a proper distance from and in parallel with the rotor axis. By use of this jig the worn corner seal member can be reshaped into a new member of slightly increased cross section making it possible to reuse the rotor as a whole without disposal of the expensive rotor proper.

10 Claims, 4 Drawing Figures PATENIEIJmczmm smear:

FEG.

1 I DRILL .IIG FOR ROTOR OF ROTARY MECHANISM BACKGROUND OF THE INVENTION The present invention relates to a tool fixture and, more particularly, to an improved drill jig for use in holding a rotor of a rotary mechanism in position when it is intended to bore or widen again, by use of a suit: able cutter drill, a, corner seal bore which has been eccentrically worn after a prolonged use.

Although the present invention is applicable to and useful in almost any type of rotary mechanism which presents a sealing requirement, such as combustion engines, fluid motors, fluid pumps, compressors, and the like, it is particularly useful in rotating combustion engines. The internal combustion engine of rotary type.

generally includes an outer body or housing having an axis, axially-spaced side walls, and a peripheral wall inter-connecting the side walls. Such rotary mechanism also includes an inner body or rotor which is rotatably mounted within a cavity defined by the inner surfaces of the side and peripheral walls of the outer housing.

The axis of the inner body or rotor is eccentric from and parallel to the axis of the cavity of the outer body, and the rotor has axially-spaced side faces disposed adjacent to the side walls of the outer body, and at least three circumferentially-spaced apex portions. The rotor is rotatable relative to the outer body, and its apex portions substantially continuously engage the inner surface of the peripheral wall of the outer housing, to thereby form a plurality of working chambers which vary in volume during the engine operation, as a result of relative rotation between the rotor and outer body.

The working chambers thus formed during the engine operation undergo a cycle of operation which includes the four phases of intake, compression, expansion and exhaust. For efficient operation of the engine, the working chambers should be sealed, and as such an effective gas seal is provided between each rotor apex portion and the inner surface of the peripheral wall of the outer body, as well as between the side faces of the rotor and the inner surfaces of the side walls of the outer housing. Insofar as an effective gas seal is concerned, the internal combustion engine under consideration is subjected to a severe working condition resulting from high and drastic temperature and pressure variations effected in the working chambers. Therefore, an apex seal member is mounted in each of apex grooves formed in the apex portions of the rotor and extending over the major length thereof. A suitable bias element such as a leaf spring is mounted in each of the apex grooves to urge the apex seal member toward the inside surface of the peripheral wall of the outer housing. Another is a corner seal member which is mounted example, of a washer type. A plurality of rows of side seal members are also fitted in side seal grooves which are formed in the side faces of the rotor, generally following the edge contours of the rotor. These side seal members are similarly biased by corresponding leaf springs toward the inner surfaces of the side walls of the outer housing.

Inorder to obtain efficient gas seal effects between the working rotor and engine housing as well as to permit the trouble-free rotation of the rotor relative to the stationary engine housing, it is considered markedly important to correctly arrange or radially align the apex groove and the corresponding corner bore. In other words, the center lines of an apex groove and an inter-related corner bore should fall in a common radius of the rotor within a limited location tolerance. For this reason, the rotor is initially machineworked correctly to effect the above alignment. 7

After a prolonged use of the engine rotor, however, the ,seal grooves, especially, the corner bores are distortedly widened or eccentrically worn due to the contact of high stress with the respective corner seal members, which continue to laterally press the interrelated inside walls of the corner bores.

More specifically, the corner seal members are made by the lateral pressure to slightly rock in the respective seal bores. As a result, the walls of the bores are worn both at the longitudinally outer portion situated rearward relative to the rotational direction of the rotor and at the inner portion situated forward relative to the direction. This will lead to a serious problem of misalignment of the center lines of the corner seal bores. In this situation, a new rotor proper is conventionally needed for substitution with a view to a continuous use of the particular combustion engine maintaining the required seal effects. If, however, widening or boring again of the eccentrically worn corner seal bores can be made in correct registry with the common plane shared between the rotor axis and the center line of the corresponding apex seal groove, then mere exchange of the old or worn corner seal member for a new member of slightly increased cross section will make it possible to reuse the rotor as a whole without disposal of the expensive rotor proper.

SUMMARY OF THE INVENTION As has been shortly described, the present invention is based on our discovery that, although the apex seal groove itself is slightly torn or worn after a prolonged use as a result of the continuous pressing of its seal member, the torn or worn portion thereof will be limited to or localized at its radially outermost and innermost wall, leaving the central portion thereof substantially untorn and unworn. This prominent phenomenon is believed to come from the fact that during operation the apex seal member will swing or rock slightly in the associated apex groove. With this in mind, the unworn central portion of the apex groove can be employed to locate or determine the accurate center line of the particular groove even after use. For this purpose, a suitable locating means may be provided in a drill jig, and the projection of the locating means is sized and arranged to be slidably fitted into the apex seal groove in a contact relationship with the untorn central portion thereof. On the other hand, the cutter drill should be guided relative to the axis of the rotor to be worked as well as to the center line of the apex groove located. To this end, the drill jig is fastened to the innerperipheral wall of the rotor, which wall usually receives a rotor bearing when the rotor as a whole is assembled into the engine unit of rotary type. By properly positioning a suitable guide means on the drill jig, therefore, the center line of the cutter drill can fall in a plane common to the rotor axis and the center line of the apex groove and can be located at an appropriate distance radially spaced from the rotor axis in parallel therewith, as required for locating the center line of the corner seal bore.

It is therefore a primary object of the invention to provide an improved drill jig for use in holding a rotor of a rotary mechanism in position when it is intended to bore or widen again, by use of a suitable cutter drill, a corner seal bore which has been eccentrically worn after a prolonged use.

Another object of the invention is to provide an improved drill jig for the above use, in which centering of the corner seal bore and accordingly correct guidance of the cutter drill is obtainable without difficulty.

A further object is to provide an improved drill jig of the above type, in which not only the rotor axis but the center line of the apex seal groove are employed to correctly locate the center line of the corresponding corner seal bore.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is an explanatory view showing a fragmentary side elevation of a rotor of a rotary mechanism in an enlarged scale;

FIG. 2 is a perspective view showing a drill jig embodying the present invention;

FIG. 3 is a longitudinal cross section of the drill jig shown in FIG. 2; and

FIG. 4 is a fragmentary perspective view of a modified drill jig assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, corner and apex portions of a rotor, as generally indicated at numeral 10, are illustrated together with the relative positions of an apex seal groove and corner seal bore. The rotor 10 may be, as shown, of generally triangular configuration and is provided with an inner peripheral wall 11 in which a rotor bearing is fittedly mounted for operation. The apex seal groove 12 is formed in the apex portion of the rotor and extends in parallel with the axis 13 of the rotor. This apex groove 12 is shown to have a width d at its unworn central portion. In the corner of the rotor is formed a corner seal bore 14 which also extends in parallel with the rotor axis 13 and merges into the apex seal groove 12 midway of its extension. The center line 12a of the apex groove 12 together with the rotor axis 13 thus forms a common plane as designated at numeral 15. This common plane 15 appears in FIG. 1 as a radius of the rotor. For effective sealing requirements, the center line 14a of the corner bore 14, which is also shown as a point, is positioned at an initial stage within a predetermined location tolerance Af. Moreover, the distance between the center line 14a and the rotor axis 13 is also preset at a value of H. Two rows of side seal grooves 16 are formed in the side faces of the rotor and generally follow the contour thereof.

From the previous discussion, the distance between the common plant 15 and the center line 14a of the corner bore 14 should be less than the allowable limit Af even after a prolonged use of the rotor. If, in this instance, the dislocation of the line 14a after use exceeds the above limit, then undesired problems will be established including leakage of the working fluids such as combustion gases around the corner seal member, not shown. In their extremity, moreover, the reduced or weakened side of the walls defining the corner bore 14 will be broken during the working operation.

In order to avoid these serious situations, replacement of the used rotor having its corner bore eccentrically worn by a new one rotor is preferable from practical point of view; but such replacement is too expensive. However, it should be appreciatedzthat this replacement can be dispensed with if the distorted or widened corner bore could be bored again and balanced in a fashion to have its center linefallwithin the allowable limit of Af. Then, it is sufficient to replace the used comer seal member by an inexpensive new member sized to be fittedly received in the newly bored corner bore. This correct boring can bev carried out with use of the drill jig according to the present invention, which will be explained in detail with reference to the remaining figures.

Turning now to FIGS. 2 and 3 showing an embodiment of the present invention, a drill jig, as generally designated at numeral 20, is provided with chucking means 21 which is, in operation, secured to or fitted into the inner peripheral wall of a rotor, as numbered at 11 in FIG. 1. The chucking means 21 includes a generally cylindrical chuck 22 having its tubular portion 22a internally tapered toward its open end. The closed end 22b of the cylindrical chuck 22 has a bore 220 formed centrally thereof. As best shown in FIG. 2, the tubular portion 22a may preferably have a plurality of slits 22d extending axially over the tapered portion thereof. This cylindrical chuck 22 as a whole is secured to a plate member 23 extending perpendicularly of the axis of the chuck 22, which is usually in alignment with the axis of the rotor as numbered at 13 in FIG. 1. The connection of the chuck 22 with the plate member 23 may be carried out by any conventional method, for example, by welding, but the angular relationship inbetween is considered markedly important. Otherwise, as better understood with reference to FIG. 3, an additional head plate 24 may be conveniently employed, to which the plate member 23 is secured with use of suitable fastening means such as a bolt 25. Through this head plate 24, in this instance, the chuck 22 is secured to the plate member 23 by the use of another fastening means such as bolt 26. The head plate 24 may preferably be provided with a bore 24a which is coextensive with the bore 22c of the chuck 22 In the chucking means 21 is also provided a chuck guide bolt or rod 27, the head portion 27a of which is counter-tapered toward its rod portion 27b in a fashion to mate with the tapered portion of the tubular portion 22a. This rod portion 27b is closely or tightly inserted into the bores 22c and 24a, with its threaded protrusion extending apart from the head.plate. The thickness of the head portion 27a is preset substantially equal to or shorter than the tapered portion of the tubular portion 22a, thus forming a space 28 defined by the inner end wall thereof together with the inner walls of the tubular portion 22a and theclosed end 22b. Within this space 28, a suitable biasing means such as a compression spring 29 may preferably be provided axially of the rod portion 27b so as to urge the chuck guide rod 27 in a direction, in which the guide rod 27 will be released from the mating contact with the tapered portion of the tubular portion 22a. In order to stably seating the compression spring 29 an annular groove may be formed in the inner wall of the head portion 27 around the base of the rod portion 27b.

A locking means, as designated at numeral 30, generally includes a cap nut 31 having its inner wall threaded to be fastened to the threaded protrusion of the head portion 27b of the chuck guide rod 27. The tight fastening of this cap nut 31 is performed by a handle 32 attached at its free end to the cap nut 31 and extending substantially perpendicularly of the axis of the same. If desired, a key member 33 may be mounted on the rod portion 27b, especially at a radially reduced portion thereof, as shown. This key member 33 may be of any conventional shape and is received in a notch formed in an inner wall of the bore 220 of the chuck 22, thus locking or, more precisely, preventing the rotation of the chuck guide rod 27 with respect to the cylindrical chuck 22 when the key member 33 is received in the notch. When it is desirable that the cap nut 31 is restricted in its axially allowed stroke, a suitable stopper 34 may be provided with a stepped shoulder which is engageable with a peripheral base edge 31a of the cap nut 31. This stopper 34 is attached to the head plate 24 with use of a suitable fastening means such as a bolt 35, with its play stroke being determined by the length of the shoulder.

At a radially outermost portion of the plate member 23, is provided a locating means which is generally indicated at numeral 40 as in the form of the letter L. The locating means 40 is, as shown, provided with a projection 41 sized and positioned to be closely received in an apex seal groove as seen from FIG. I. It should be noted here that the radial extension of the projection 41 will meet the axis of the chuck guide rod 27 and accordingly the rotor axis 13. As best understood from FIG. 2, it should also be noted that the width d of the particular projection 41 is precisely sized to be slidably fitted into the apex seal groove. If desired, the locating means 40 may be removably secured to the plate member 23 by the use of a locking pin 42. Thus, the center line of the apex seal groove is correctly indexed or located by the particular arrangement and configulation of the locating means.

Guide means 50 may be removably secured to the plate member 23 either integrally with or separately from the locating means 40, with the center line thereof being positioned to fall substantially in a common plane, as numbered at in FIG. 1 shared between the rotor axis 13 and the center line 12a of the apex seal groove 12. It is also important in this instance that the center line of the guide means 50 is positioned to be radially spaced at a distance H, as explained with reference to H6. 1, from the rotor axis 13. The guide means 50 is shown as a cylindrical body or a guide bushing, but may be of any hollow structure if it can guide therethrough a boring tool or cutter drill, not shown. It should be appreciated that the location of the center line of the guide means 50 can thus be automatically extracted from the relative arrangement of the chucking, locking and locating means 20, 30 and 40.

When it is intended to prepare the boring operation of the drill jig the chuck 22 is closely inserted into the rotor inner wall ll together with the elements of the jig 20. Then, the locating member 40 is fitted into the apex seal groove 12 after adjusting the angular position of the chuck 22 in the rotor wall 11. With all these elements held in position, the fastening cap nut 31 is screwed on the threaded portion of the rod portion 2712 by turning the handle 32. As this turning of the handle proceeds, the key member 33 is captured by the notch formed in the bore of the chuck 22, thus preventing further rotation of the chuck guide rod 27 with respect to the chuck 22 and other elements. With the further turn of the handle 32, as a result, the chuck guide 27 is moved toward the cap nut 31. Then, the tapered surfaces of the chuck 22 and the chuck guide rod 27 are made contact with each other and the tapered tubular portion 220 begins to radially expand with the aid of slits 220' formed therein. Thus, the drill jig 20 is locked up in the proper position for the subsequent boring operation.

At the succeeding step, a suitable cutter drill having a slightly larger effective diameter than that of the initial one is inserted into and guided by the cutter guide so as to machinework the corner seal bore 14. During the actual boring operation, the locating member 40 may preferably be removed from the jig body so as to be free from any damage. The operation itself is, however, well known, and as such the detailed expalanation thereof will be omitted.

After the boring operation has been completed, the cap nut 31 is loosened by oppositely turning the handle 32, and then the compression spring 29 having been confined in the space 28 under high compression begins to movethe chuck guide rod 27 in a direction to depart from the chuck 22. With this action of the spring, the contact relationship between the chuck 22 and the chuck guide rod 27 is finally released to afford the former its original relative position. At this instance, the detachment of the drill jig 20 from the rotor is easily carried out by manually pulling out the jig proper.

In modification, the head plate 24 may be dispensed with and then the chuck 22 is directly fastened to the plate member 23.

Turning now to FIG. 4, the projection 41' of the locating member 40 is shown to have a circular cross section of the same diameter d. In this assembled embodiment, a similar unit of the locating member 40 and the cutter guide 50 is mounted on the plate member 23 at every apex portion of the rotor. Then, every corner seal bore is simultaneously indexed and bored with use of cutter drills in number corresponding to that of the apex portions of the rotor. A close attention should be paid to the fact that the cross section of the projection 41 is circular. This is because, if the cross section is rectangular as shown in FIG. 2, the play or allowance of movement of the projection 41' in the apex seal groove is highly restricted to an extent to make it impossible to concurrently fit all the projections into the corresponding grooves. Although the slight allowance of movement will degrade the correct centering of the respective projections, especially the resultant distance H between the center line of the corner bore and the rotor axis, the degraded centering can be limited within a predetermined general tolerance. Therefore, high cutting performance is obtainable from this modification.

As has been described in the above, the present invention can provide a drill jig for use in reboring an ec- 7 centrically worn corner seal bore without disposing of the rotor as a whole. This ensures a prolonged use of the rotor without unnecessary change to a new one and accordingly contributes to economy in the art of a rotary mechanism.

What is claimed is:

1. A drilling jig for holding a cutter drill in position on a rotor of a rotary mechanism, said rotor having an aperture at its axis, and spaced from the axis, an apex seal groove and an adjacent corner seal bore; the center lines of the seal groove and corner seal bore lying in a plane common to the axis of the rotor, said jig comprising:

a. chucking means attachable to said rotor for securing the jig in a predetermined position with respect to the axis of the rotor;

b. locating means having a projection shaped to be slidably fitted into the apex seal groove;

c. connecting means for connecting the chucking means and the locating means;

d. guide means mounted on the connecting means for guiding said cutter drill therethrough and having its axis lying in a plane including the axes of the chucking means and locating means;

e. locking means mounted on said chucking means for locking it in position on the rotor.

2. A drill jig according to claim 1 in which the projection of the locating means is an elongated tongue having its axis lying in a plane including the axes of the chucking means and guide means.

3. A drill jig according to claim 1, wherein said chucking means includes a generally cylindrical chuck having an internally tapered open end and a centrally bored closed end, said open end being provided with a plurality of axial slots and being sized to be closely inserted into the inner peripheral wall of the aperture of said rotor in alignment with said rotor axis, a plate member secured to said chuck perpendicularly of the axis thereof and mounting thereon said locating means and guide means, and a chuck guide rod having a head portion countertapered to mate with the taper of said chuck and a rod portion closely inserted into the bore of the closed end of said chuck with its threaded protrusion extending apart from said plate member; and

wherein said locking means includes a cap nut having its inner wall threaded to be fastened to the threaded protrusion of said chuck guide rod, and a handle attached to the free end of said cup nut for effecting tightening and loosening of said cup nut.

4. A drill jig according to claim 3, wherein said locking means further includes a key member mounted on the rod portion of said chuck guide rod for being received in a notch formed in an inner wall of the bore of said chuck so as to prevent the rotation of said chuck guide rod with respect to said chuck when said cup nut is screwed.

5. A drill jig according to claim 3, wherein said chucking means further includes a head plate secured to said plate member and the closed end of said chuck to thereby establish a secure connection therebetween and provided with a bore through which the rod portion of said chuck guide rod extends.

6. A drill jig according to claim 5, wherein said locking means further includes a stopper attached to said head plate and having a stepped shoulder engageable with a peripheral edge of said cup nut for providing a play stroke determined by the length of said shoulder.

7. A drill jig according to claim 3, further comprising biasing means for urging said chuck guide rod in a direction in which said guide rod is released from the mating contact with the tapered portion of said chuck.

8. A drill jig according to claim 7, wherein said biasing means includes a compression spring accommodated axially of said chuck guide rod within a space defined by the inner wall of the head portion of said guide rod and by the inner walls of said chuck.

9. A drill jig according to claim 8, wherein said compression spring is stably seated in an annular groove formed in the inner wall of said head portion around the base of said rod portion.

10. A drill jig according to claim 1, wherein said guide means includes a guide bushing having a center line positioned to fall in said common plane and to be spaced radially of said rotor at a predetermined distance from said rotor axis. 

1. A drilling jig for holding a cutter drill in position on a rotor of a rotary mechanism, said rotor having an aperture at its axis, and spaced from the axis, an apex seal groove and an adjacent corner seal bore; the center lines of the seal groove and corner seal bore lying in a plane common to the axis of the rotor, said jig comprising: a. chucking means attachable to said rotor for securing the jig in a predetermined position with respect to the axis of the rotor; b. locating means having a projection shaped to be slidably fitted into the apex seal groove; c. connecting means for connecting the chucking means and the locating means; d. guide means mounted on the connecting means for guiding said cutter drill therethrough and having its axis lying in a plane including the axes of the chucking means and locating means; e. locking means mounted on said chucking means for locking it in position on the rotor.
 2. A drill jig according to claim 1 in which the projection of the locating means is an elongated tongue having its axis lying in a plane including the axes of the chucking means and guide means.
 3. A drill jig according to claim 1, wherein said chucking means includes a generally cylindrical chuck having an internally tapered open end and a centrally bored closed end, said open end being provided with a plurality of axial slots and beinG sized to be closely inserted into the inner peripheral wall of the aperture of said rotor in alignment with said rotor axis, a plate member secured to said chuck perpendicularly of the axis thereof and mounting thereon said locating means and guide means, and a chuck guide rod having a head portion countertapered to mate with the taper of said chuck and a rod portion closely inserted into the bore of the closed end of said chuck with its threaded protrusion extending apart from said plate member; and wherein said locking means includes a cap nut having its inner wall threaded to be fastened to the threaded protrusion of said chuck guide rod, and a handle attached to the free end of said cup nut for effecting tightening and loosening of said cup nut.
 4. A drill jig according to claim 3, wherein said locking means further includes a key member mounted on the rod portion of said chuck guide rod for being received in a notch formed in an inner wall of the bore of said chuck so as to prevent the rotation of said chuck guide rod with respect to said chuck when said cup nut is screwed.
 5. A drill jig according to claim 3, wherein said chucking means further includes a head plate secured to said plate member and the closed end of said chuck to thereby establish a secure connection therebetween and provided with a bore through which the rod portion of said chuck guide rod extends.
 6. A drill jig according to claim 5, wherein said locking means further includes a stopper attached to said head plate and having a stepped shoulder engageable with a peripheral edge of said cup nut for providing a play stroke determined by the length of said shoulder.
 7. A drill jig according to claim 3, further comprising biasing means for urging said chuck guide rod in a direction in which said guide rod is released from the mating contact with the tapered portion of said chuck.
 8. A drill jig according to claim 7, wherein said biasing means includes a compression spring accommodated axially of said chuck guide rod within a space defined by the inner wall of the head portion of said guide rod and by the inner walls of said chuck.
 9. A drill jig according to claim 8, wherein said compression spring is stably seated in an annular groove formed in the inner wall of said head portion around the base of said rod portion.
 10. A drill jig according to claim 1, wherein said guide means includes a guide bushing having a center line positioned to fall in said common plane and to be spaced radially of said rotor at a predetermined distance from said rotor axis. 